Etherified carbamate crosslinking agents and their use in curable compositions, particularly film-forming compositions

ABSTRACT

The present invention provides a reaction product of reactants comprising: 
     a) a polyisocyanate; 
     b) a hydroxyalkyl carbamate; 
     c) an aldehyde; and 
     d) at least one monohydric alcohol. 
     Additionally provided is a composition of matter comprising the structure:                    
     where Q is a multi-valent organic moiety containing urethane linkages; X is H, —CH 2 OH, or —CH 2 OR′; R′ is an alkyl or aryl group having from 1 to 12 carbon atoms; and y is at least 2. The reaction product described above may have the structure (i). 
     The reaction product and composition of matter are suitable for use as crosslinking agents in a variety of curable compositions further comprising at least one polymer having functional groups that are reactive with the crosslinking agent. Such curable compositions may be used as film-forming compositions.

FIELD OF THE INVENTION

The present invention relates to crosslinking agents having etherifiedcarbamate functionality, and to curable compositions containing them.

BACKGROUND OF THE INVENTION

Coating compositions used in the original automotive equipment marketare being called to more and more stringent performance requirements.Coating systems are expected to provide lasting weatherability,durability, resistance to acid etching, and mar resistance, whilemaintaining outstanding appearance properties. Coating systems used incertain applications, such as on plastic substrates, must also beflexible. Additionally, automotive coating compositions are expected tobe available in environmentally friendly formulations.

Some coating compositions cured via acid-epoxy cure mechanisms, whileproviding excellent acid etch resistance, offer only marginal marresistance. Conventional coating compositions cured with aminoplastcrosslinking agents have been known for superior durability, but it hasonly been recently that aminoplast-cured coatings providing acid etchresistance have become available. Moreover, aminoplast-cured systemstypically suffer from high photo-oxidation rates due to the breakdown ofthe aminotriazine ring inherently found in most aminoplast resins. Suchdegradation is due to prolonged exposure to ultraviolet light.

It would be desirable to provide crosslinking agents and curablecompositions suitable for use as film-forming compositions in theautomotive and industrial markets that overcome the drawbacks of theprior art, providing both appearance and performance properties nowconsidered essential in automotive applications.

SUMMARY OF THE INVENTION

The present invention provides a reaction product of reactantscomprising:

a) a polyisocyanate;

b) a hydroxyalkyl carbamate;

c) an aldehyde; and

d) at least one monohydric alcohol. The reaction product is suitable foruse in a variety of curable compositions, which are also provided.

Additionally provided is a composition of matter comprising thestructure:

wherein Q is a multi-valent organic moiety containing urethane linkages;X is H, —CH₂OH, or —CH₂OR′; R′ is an alkyl or aryl group having from 1to 12 carbon atoms; and y is at least 2. The reaction product describedabove may have the structure (i).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Other than in the operating examples, or where otherwise indicated, allnumbers expressing quantities of ingredients, reaction conditions, andso forth used in the specification and claims are to be understood asbeing modified in all instances by the term “about.” Accordingly, unlessindicated to the contrary, the numerical parameters set forth in thefollowing specification and attached claims are approximations that mayvary depending upon the desired properties to be obtained by the presentinvention. At the very least, and not as an attempt to limit theapplication of the doctrine of equivalents to the scope of the claims,each numerical parameter should at least be construed in light of thenumber of reported significant digits and by applying ordinary roundingtechniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical values, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

Also, it should be understood that any numerical range recited herein isintended to include all sub-ranges subsumed therein. For example, arange of “1 to 10” is intended to include all sub-ranges between (andincluding) the recited minimum value of 1 and the recited maximum valueof 10, that is, having a minimum value equal to or greater than 1 and amaximum value of equal to or less than 10.

The reaction product of the present invention is typically prepared byreacting together:

a) a polyisocyanate;

b) a hydroxyalkyl carbamate;

c) an aldehyde; and

d) at least one monohydric alcohol.

The polyisocyanate a) may be selected from one or more polyisocyanates,such as diisocyanates and triisocyanates including biurets andisocyanurates. Biurets of any suitable diisocyanate including1,4-tetramethylene diisocyanate and 1,6-hexamethylene diisocyanate maybe used as reactant a) in the preparation of the reaction product of thepresent invention. Also, biurets of cycloaliphatic diisocyanates, suchas isophorone diisocyanate and 4,4′-methylene-bis-(cyclohexylisocyanate), can be employed. Examples of suitable aralkyl diisocyanatesfrom which biurets may be prepared are meta-xylylene diisocyanate andα,α,α′,α′-tetramethylmeta-xylylene diisocyanate. The diisocyanatesthemselves may also be used as reactant a) in the preparation of thereaction product of the present invention.

Trifunctional isocyanates may also be used as reactant a), for example,trimers of isophorone diisocyanate, triisocyanato nonane,triphenylmethane triisocyanate, 1,3,5-benzene triisocyanate,2,4,6-toluene triisocyanate, an adduct of trimethylol and tetramethylxylene diisocyanate sold under the trade name CYTHANE 3160 by CYTECIndustries, and DESMODUR N 3300, which is the isocyanurate ofhexamethylene diisocyanate, available from Bayer Corporation.Specifically used polyisocyanates are cyclic isocyanates, particularly,isocyanurates of diisocyanates such as hexamethylene diisocyanate andisophorone diisocyanate.

The polyisocyanate used as reactant a) may also be one of thosedisclosed above, chain extended with one or more polyamines and/orpolyols using suitable materials and techniques known to those skilledin the art.

In the preparation of the reaction product of the present invention, thepolyisocyanate reactant a) is used in an amount of 5 to 70 percent byweight, based on the total weight of reactants used to prepare thereaction product.

The hydroxyalkyl carbamate used as reactant b) typically contains about3 to about 7 carbon atoms. Examples include hydroxyethyl carbamate,hydroxypropyl carbamate, hydroxybutyl carbamate, and the like. Reactionproducts of ammonia and hydroxyl functional carbonates, such as glycerincarbonate, are also suitable. Hydroxypropyl carbamate and hydroxyethylcarbamate are most often used. Reactant b) is used in an amount of 1 to60 percent by weight, based on the total weight of reactants used toprepare the reaction product.

The aldehyde c) most often used in the preparation of the reactionproduct of the present invention is formaldehyde. Other aldehydes, suchas acetaldehyde, propanaldehyde, butyraldehyde, furfural, benzaldehyde,acrolein, methacrolein, and glyoxal are also suitable. The aldehyde c)is used in an amount of 1 to 60 percent by weight, based on the totalweight of reactants used to prepare the reaction product.

Alkylol groups formed during the reaction of a), b), and c) are at leastpartially etherified by reaction with at least one monohydric alcohold). Any monohydric alcohol can be employed for this purpose.Particularly suitable alcohols may have up to 12 carbon atoms, mosttypically have from 1 to 6 carbon atoms, and include methanol, ethanol,n-propanol, isopropanol, n-butanol, isobutanol, pentanol, hexanol,cyclohexanol, and others, as well as benzyl alcohol and other aromaticalcohols, cyclic alcohols, such as cyclohexanol, monoethers of glycols,and halogen-substituted or other substituted alcohols, such as3-chloropropanol and butoxyethanol. Most commonly, methanol, isobutanol,and/or n-butanol are used.

In the preparation of the reaction product of the present invention, themonohydric alcohol d) is used in an amount of 1 to 70 percent by weight,based on the total weight of reactants used to prepare the reactionproduct.

The urethane oligomer or polymer having carbamate functional groups maybe alkylolated by reaction with an aldehyde. Examples of suitablealdehydes include those mentioned above, with formaldehyde being mostoften used. Alkylolation may be performed in an aqueous or alcoholicmedium, using techniques known to those skilled in the art; for example,at temperatures of about 10° C. to about 100° C. in aqueous medium, andabout 10° C. to about 170° C. in organic medium.

The alkylolated polymer or oligomer may then optionally be etherified byreaction with an alcohol using conventional techniques. Suitablealcohols contain about 1 to about 12 carbon atoms and include methanol,ethanol, n-propanol, isopropanol, n-butanol, isobutanol, pentanol, andcyclohexanol. Isobutanol, n-butanol, and methanol are most often used.

Alkylolation and etherification of the carbamate functional polymer oroligomer may be done in one step by reacting the carbamate functionalpolymer or oligomer with an aldehyde in an acidic, alcoholic medium suchthat the alcohol solvent which is in stoichiometric excess participatesin the reaction. Alternatively, the alkylolation may first be carriedout in a basic aqueous or alcoholic medium. After the alkylolationreaction is complete, the reaction mixture is treated with acid in orderto neutralize the base and establish an acidic pH. If the reaction wasrun under aqueous conditions, the etherifying alcohol can be added tothe reaction mixture prior to acidification. The reaction mixture isthen typically heated to accomplish the etherification reaction.

In either of the scenarios outlined above, if the etherifying alcohol isimmiscible with water the reaction can be heated to reflux and water canbe removed via azeotropic distillation in order to drive the equilibriumin favor of the etherification reaction. Partial etherification ispossible by stopping the reaction once an amount of water is removedcorresponding to the desired degree of etherification. If the alcohol ismiscible with water (e.g. methanol) the reaction mixture is simplyheated and held until the desired degree of etherification or systemequilibrium is reached. If desired, water can be stripped from thereaction mixture with the alcohol once the reaction is complete at aneutral or slightly basic pH to prevent gelling the reaction product.

In one embodiment of the invention there is provided a composition ofmatter comprising the structure:

wherein Q is a multi-valent organic moiety containing urethane linkages;X is H, —CH₂OH, or —CH₂OR′; R′ is an alkyl or aryl group having from 1to 12 carbon atoms; and y is at least 2. The reaction product describedabove may have the structure (i). As mentioned earlier, R′ is typicallyan alkyl or aryl group having from 1 to 12 carbon atoms, and may belinear or branched, cyclic, aralkyl, or alkaryl, and may containheteroatom substituents. R′ is most often the residue of a monohydricalcohol and contains from 1 to 6 carbon atoms.

The moiety Q typically is derived from a polyisocyanate and contains atleast 2 urethane linkages. The moiety Q may contain groups of thestructure —N—CH₂—OR′, formed during etherification of the urethanelinkages. Q may contain cyclic moieties, particularly when derived fromisocyanurates. In a specific embodiment, Q has the structure:

wherein X and y are as described above, R″ is a divalent group, and R′″is a residue of a polyisocyanate. R″ may be linear or branched, cyclic,alkaryl or aralkyl and may contain heteroatom substituents. R″ is mostoften an alkylene group having from 1 to 6 carbon atoms. R′″ is mostoften a residue of an isocyanurate.

In a separate embodiment of the present invention, the reaction productor composition of matter described above is present as a crosslinkingagent in a curable composition comprising:

a) the reaction product or composition of matter described above,typically present in an amount of 1 to 99, often 1 to 50 percent byweight based on the total weight of resin solids in the curablecomposition; and

b) at least one polymer having functional groups that are reactive withthe reaction product or composition of matter of a), typically presentin a total amount of 1 to 99, often 20 to 85 percent by weight based onthe total weight of resin solids in the curable composition. Thecomposition of this embodiment is suitable for use as a curablefilm-forming composition.

Useful functional polymers for use as component b) in the curablecomposition of the present invention include vinyl polymers, acrylicpolymers, polyesters, including alkyds, polyurethanes, polyethers andcopolymers, and mixtures thereof. As used herein, the term “polymer” ismeant to refer to oligomers and both homopolymers and copolymers. Unlessstated otherwise, as used in the specification and the claims, molecularweights are number average molecular weights for polymeric materialsindicated as “M_(n)” and obtained by gel permeation chromatography usinga polystyrene standard in an art-recognized manner.

The polymer (b) may comprise reactive functional groups selected fromhydroxyl, carboxylic acid, amide, thiol, urea, carbamate, thiocarbamate,and mixtures thereof. In one embodiment of the present invention, thepolyfunctional polymer (b) comprises carbamate functional groups of thestructure:

wherein Z is H, or an alkyl or aryl group containing 1 to 12 carbonatoms and may be linear or branched, cyclic, alkaryl or aralkyl and maycontain heteroatom substituents.

Suitable functional polymers include acrylic polymers such as copolymersof one or more alkyl esters of acrylic acid or methacrylic acid,optionally together with one or more other polymerizable ethylenicallyunsaturated monomers. Useful alkyl esters of acrylic acid or methacrylicacid include aliphatic alkyl esters containing from 1 to 30, and often 4to 18 carbon atoms in the alkyl group. Non-limiting examples includemethyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylacrylate, butyl acrylate, and 2-ethylhexyl acrylate. Suitable othercopolymerizable ethylenically unsaturated monomers include vinylaromatic compounds such as styrene and vinyl toluene; nitrites such asacrylonitrile and methacrylonitrile; vinyl and vinylidene halides suchas vinyl chloride and vinylidene fluoride and vinyl esters such as vinylacetate.

The acrylic polymer can include hydroxyl functional groups, which areoften incorporated into the polymer by including one or more hydroxylfunctional monomers in the reactants used to produce the copolymer.Useful hydroxyl functional monomers include hydroxyalkyl acrylates andmethacrylates, typically having 2 to 4 carbon atoms in the hydroxyalkylgroup, such as hydroxyethyl acrylate, hydroxypropyl acrylate,4-hydroxybutyl acrylate, hydroxy functional adducts of caprolactone andhydroxyalkyl acrylates, and corresponding methacrylates. The acrylicpolymer can be prepared with N-(alkoxymethyl)acrylamides andN-(alkoxymethyl) methacrylamides, which result in self-crosslinkingacrylic polymers.

Hydroxyl functional groups may be incorporated into the acrylic polymerby using one or more ethylenically unsaturated beta-hydroxy esterfunctional monomers. Such monomers can be prepared from ethylenicallyunsaturated, epoxy functional monomers reacted with carboxylic acidshaving from about 1 to about 20 carbon atoms, often from about 13 toabout 20 carbon atoms, or from ethylenically unsaturated acid functionalmonomers reacted with epoxy compounds containing at least 4 carbon atomsthat are not polymerizable with the ethylenically unsaturated acidfunctional monomer.

Useful ethylenically unsaturated, epoxy functional monomers includeglycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether,methallyl glycidyl ether, 1:1 (molar) adducts of ethylenicallyunsaturated monoisocyanates such asmeta-isopropenyl-alpha,alpha-dimethylbenzyl isocyanate with hydroxyfunctional monoepoxides such as glycidol, and glycidyl esters ofpolymerizable polycarboxylic acids such as maleic acid, fumaric acid,and crotonic acid. Most often used are the epoxy-functional acrylatessuch as glycidyl acrylate, epoxy functional methacrylates such asglycidyl methacrylate, or mixtures thereof. Glycidyl acrylate andglycidyl methacrylate are most often used.

Examples of saturated carboxylic acids include saturated monocarboxylicacids such as those which are noncrystalline at room temperature,particularly those having branched structures. Isostearic acid is mostoften used. As used herein, the term “saturated” as in the phrase“saturated monocarboxylic acid” is intended to denote the absence ofethylenic unsaturation but is not intended to exclude aromaticunsaturation as found, for example, in a benzene ring.

Useful ethylenically unsaturated acid functional monomers includemonocarboxylic acids such as acrylic acid, methacrylic acid, andcrotonic acid; dicarboxylic acids such as itaconic acid, maleic acid,and fumaric acid; and monoesters of dicarboxylic acids such as monobutylmaleate and monobutyl itaconate. The ethylenically unsaturated acidfunctional monomer and epoxy compound are typically reacted in a 1:1equivalent ratio. The epoxy compound does not contain ethylenicunsaturation which would participate in free radical-initiatedpolymerization with the unsaturated acid functional monomer. Usefulepoxy compounds include 1,2-pentene oxide, styrene oxide and glycidylesters or ethers, typically containing from 8 to 30 carbon atoms, suchas butyl glycidyl ether, octyl glycidyl ether, phenyl glycidyl ether,and para-(tertiary butyl) phenyl glycidyl ether. Most often-usedglycidyl esters include those of the structure:

where R is a hydrocarbon radical containing from about 4 to about 26carbon atoms. Typically, R is a branched hydrocarbon group having fromabout 8 to about 10 carbon atoms, such as neopentanoate, neoheptanoateor neodecanoate. Suitable glycidyl esters of carboxylic acids includethose commercially available from Shell Chemical Company under thetrademark CARDURA® E; and from Exxon Chemical Company under thetrademark GLYDEXX®-10.

Carbamate functional groups can be included in the acrylic polymer bycopolymerizing the acrylic monomers with a carbamate functional vinylmonomer, such as a carbamate functional alkyl ester of methacrylic acid,or by reacting a hydroxyl functional acrylic polymer with a lowmolecular weight carbamate functional material, such as can be derivedfrom an alcohol or glycol ether, via a transcarbamoylation reaction. Inthis reaction, a low molecular weight carbamate functional materialderived from an alcohol or glycol ether is reacted with the hydroxylgroups of the acrylic polyol, yielding a carbamate functional acrylicpolymer and the original alcohol or glycol ether.

The low molecular weight carbamate functional material derived from analcohol or glycol ether may be prepared by reacting the alcohol orglycol ether with urea in the presence of a catalyst. Suitable alcoholsinclude lower molecular weight aliphatic, cycloaliphatic, and aromaticalcohols such as methanol, ethanol, propanol, butanol, cyclohexanol,2-ethylhexanol, and 3-methylbutanol. Suitable glycol ethers includeethylene glycol methyl ether and propylene glycol methyl ether.Propylene glycol methyl ether and methanol are most often used. Otheruseful carbamate functional monomers are disclosed in U.S. Pat. No.5,098,947, which is incorporated herein by reference.

Amide functionality may be introduced to the acrylic polymer by usingsuitably functional monomers in the preparation of the polymer, or byconverting other functional groups to amido-groups using techniquesknown to those skilled in the art. Likewise, other functional groups maybe incorporated as desired using suitably functional monomers ifavailable or conversion reactions as necessary.

The acrylic polymer can be prepared by solution polymerizationtechniques. In conducting the reaction, the monomers are heated,typically in the presence of a free radical initiator such as organicperoxides or azo compounds, for example, benzoyl peroxide orN,N-azobis(isobutyronitrile) and optionally a chain transfer agent, inan organic solvent in which the ingredients as well as the resultantpolymer product are compatible. Typically, the organic solvent ischarged to a reaction vessel and heated to reflux, optionally under aninert atmosphere. The monomers and other free radical initiator areadded slowly to the refluxing reaction mixture. After the addition iscomplete, some additional initiator may be added and the reactionmixture held at an elevated temperature to complete the reaction.

The acrylic polymer typically has a number average molecular weight offrom about 900 to 13,000, often from about 1000 to 5000 as determined bygel permeation chromatography using a polystyrene standard. The acrylicpolymers have functional group equivalent weights less than about 5000,often within the range of about 140 to 2500, based on equivalents ofreactive functional groups. The term “equivalent weight” is a calculatedvalue based on the relative amounts of the various ingredients used inmaking the specified material and is based on the solids of thespecified material. The relative amounts are those that result in thetheoretical weight in grams of the material, such as a polymer producedfrom the ingredients, and yield a theoretical number of the particularfunctional group that is present in the resulting polymer. Thetheoretical polymer weight is divided by the theoretical number to givethe equivalent weight. For example, hydroxyl equivalent weight is basedon the equivalents of reactive pendant and/or terminal hydroxyl groupsin a hydroxyl-containing polymer.

As discussed above, the functional polymer used in the curablefilm-forming composition of the present invention may alternatively bean alkyd resin or a polyester. Such polymers can be prepared in a knownmanner by condensation of polyhydric alcohols and polycarboxylic acids.Suitable polyhydric alcohols include ethylene glycol, propylene glycol,butylene glycol, 1,6-hexylene glycol, neopentyl glycol, diethyleneglycol, glycerol, trimethylol propane, 2,2,4-trimethyl-1,3-pentanediol,2,2-dimethyl-3-hydroxypropyl-2,2-dimethyl-3-hydroxypropionate,pentaerythritol, and the like. Suitable polycarboxylic acids includesuccinic acid, adipic acid, azelaic acid, sebacic acid, maleic acid,fumaric acid, phthalic acid, tetrahydrophthalic acid, hexahydrophthalicacid, methylhexahydrophthalic acid, and trimellitic acid. Besides thepolycarboxylic acids mentioned above, functional equivalents of theacids such as anhydrides where they exist or lower alkyl esters of theacids such as methyl esters can be used. Polyesters prepared frompolycarboxylic acids and epoxides or polyepoxides as known to thoseskilled in the art may also be used. Where it is desired to produceair-drying alkyd resins, suitable drying oil fatty acids can be used andinclude those derived from linseed oil, soya bean oil, tall oil,dehydrated castor oil, or tung oil. The polyesters and alkyd resins cancontain a portion of free hydroxyl and/or carboxyl groups that areavailable for further crosslinking reactions by adjusting thestoichiometry of the reactants used to prepare the polyester or alkyd.

Carbamate functional groups may be incorporated into the polyester byfirst forming a hydroxyalkyl carbamate which can be reacted with thepolyacids and polyols used in forming the polyester. The hydroxyalkylcarbamate is condensed with acid functionality on the polyester,yielding terminal carbamate functionality. Carbamate functional groupsmay also be incorporated into the polyester by reacting terminalhydroxyl groups on the polyester with a low molecular weight carbamatefunctional material via a transcarbamoylation process similar to the onedescribed above in connection with the incorporation of carbamate groupsinto the acrylic polymers, or by reacting isocyanic acid with a hydroxylfunctional polyester.

Other functional groups, such as amide, thiol, urea, and thiocarbamate,may be incorporated into the polyester or alkyd resin as desired usingsuitably functional reactants if available, or conversion reactions asnecessary to yield the desired functional groups. Such techniques areknown to those skilled in the art.

A particularly suitable polyester may be prepared from trimethylolpropane, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, andhexahydrophthalic anhydride, transcarbamoylated with methyl carbamate.The preparation of this polyester is described in the examples thatfollow.

The polyester polymer typically has a number average molecular weight offrom about 600 to 3000, often from about 800 to 1500 as determined bygel permeation chromatography using a polystyrene standard, and afunctional group equivalent weight within the range of about 200 to1500, often about 300 to 400, based on equivalents of reactive pendantor terminal functional groups.

Polyurethanes can also be used as the functional polymer in the curablefilm-forming composition. Useful polyurethanes include polymeric polyolswhich are prepared by reacting polyhydric alcohols, polyester polyols oracrylic polyols, such as those mentioned above or polyether polyols,such as those mentioned below with a polyisocyanate such that the OH/NCOequivalent ratio is greater than 1:1 so that free hydroxyl groups arepresent in the product. Alternatively, isocyanate functionalpolyurethanes may be prepared using similar reactants in relativeamounts such that the OH/NCO equivalent ratio is less than 1:1, and theisocyanate functional polyurethanes may be modified to containfunctional groups that are reactive with the reaction product orcomposition of matter of a).

The organic polyisocyanate that is used to prepare the polyurethanepolymer can be an aliphatic or aromatic polyisocyanate or mixturesthereof. Diisocyanates are most often used, although higherpolyisocyanates can be used in place of or in combination withdiisocyanates. Examples of suitable aromatic diisocyanates include4,4′-diphenylmethane diisocyanate and toluene diisocyanate. Examples ofsuitable aliphatic diisocyanates include straight chain aliphaticdiisocyanates such as 1,6-hexamethylene diisocyanate. Also,cycloaliphatic diisocyanates such as isophorone diisocyanate and4,4′-methylene-bis-(cyclohexyl isocyanate) can be used. Examples ofsuitable higher polyisocyanates include 1,2,4-benzene triisocyanate andpolymethylene polyphenyl isocyanate. Additional polyisocyanates such asthose disclosed above in the preparation of the reaction product of thepresent invention may also be used.

Terminal and/or pendent carbamate functional groups can be incorporatedinto the polyurethane by reacting a polyisocyanate with a polymericpolyol containing the terminal/pendent carbamate groups. Alternatively,carbamate functional groups can be incorporated into the polyurethane byreacting a polyisocyanate with a polyol and a hydroxyalkyl carbamate orisocyanic acid as separate reactants. Carbamate functional groups canalso be incorporated into the polyurethane by reacting a hydroxylfunctional polyurethane with a low molecular weight carbamate functionalmaterial via a transcarbamoylation process similar to the one describedabove in connection with the incorporation of carbamate groups into theacrylic polymer. Additionally, an isocyanate functional polyurethane canbe reacted with a hydroxyalkyl carbamate to yield a carbamate functionalpolyurethane.

Other functional groups such as amide, thiol, urea, and thiocarbamatemay be incorporated into the polyurethane as desired using suitablyfunctional reactants if available, or conversion reactions as necessaryto yield the desired functional groups. Such techniques are known tothose skilled in the art.

The polyurethane typically has a number average molecular weight of fromabout 600 to 3000, often from about 800 to 1500 as determined by gelpermeation chromatography using a polystyrene standard. Thepolyurethanes typically have functional group equivalent weights withinthe range of about 200 to 1500, based on equivalents of reactivefunctional groups.

Examples of polyether polymers used in the curable composition of thepresent invention are polyalkylene ether polyols including those havingthe following structural formula:

where the substituent R₁ is hydrogen or lower alkyl containing from 1 to5 carbon atoms including mixed substituents, and n is typically from 2to 6 and m is from 8 to 100 or higher. Included arepoly(oxytetramethylene) glycols, poly(oxytetraethylene) glycols,poly(oxy-1,2-propylene) glycols, and poly(oxy-1,2-butylene) glycols.

Also useful are polyether polyols formed from oxyalkylation of variouspolyols, for example, diols such as ethylene glycol, 1,6-hexanediol,Bisphenol A and the like, or other higher polyols such astrimethylolpropane, pentaerythritol, and the like. Polyols of higherfunctionality that can be utilized as indicated can be made, forinstance, by oxyalkylation of compounds such as sucrose or sorbitol. Onecommonly utilized oxyalkylation method is reaction of a polyol with analkylene oxide, for example, propylene or ethylene oxide, in thepresence of an acidic or basic catalyst. Polyethers used most ofteninclude those sold under the names TERATHANE and TERACOL, available fromE. I. du Pont de Nemours and Company, Inc., and POLYMEG, available fromQ O Chemicals, Inc., a subsidiary of Great Lakes Chemical Corp.

Most often, pendant or terminal carbamate functional groups may beincorporated into the polyethers by a transcarbamoylation reaction asdescribed above.

Other functional groups such as amide, thiol, urea, and thiocarbamatemay be incorporated into the polyether as desired using suitablyfunctional reactants if available, or conversion reactions as necessaryto yield the desired functional groups. The polyether polymer typicallyhas a number average molecular weight of from about 500 to 5000, moretypically from about 900 to 3200 as determined by gel permeationchromatography using a polystyrene standard, and an equivalent weight ofwithin the range of 140 to 2500, often about 500, based on equivalentsof reactive pendant or terminal functional groups.

The curable composition may further include one or more auxiliarycrosslinking agents such as free and/or capped polyisocyanates; triazinecompounds of the formula: C₃N₃(NHCOXR)₃, wherein X is nitrogen, oxygen,sulfur, phosphorus, or carbon, and R is a lower alkyl group having oneto twelve carbon atoms, or mixtures of lower alkyl groups, andconventional aminoplast crosslinking agents.

Suitable polyisocyanates include any of those disclosed above. Anysuitable aliphatic, cycloaliphatic, or aromatic alkyl monoalcohol orphenolic compound may be used as a capping agent for the polyisocyanate.Examples include lower aliphatic alcohols such as methanol, ethanol, andn-butanol; cycloaliphatic alcohols such as cyclohexanol; aromatic-alkylalcohols such as phenyl carbinol and methylphenyl carbinol; and phenoliccompounds such as phenol itself and substituted phenols wherein thesubstituents do not affect coating operations, such as cresol andnitrophenol. Glycol ethers may also be used as capping agents. Suitableglycol ethers include ethylene glycol butyl ether, diethylene glycolbutyl ether, ethylene glycol methyl ether and propylene glycol methylether.

Other suitable capping agents include pyrazoles such as 3,5-dimethylpyrazole, oximes such as methyl ethyl ketoxime, acetone oxime andcyclohexanone oxime, lactams such as epsilon-caprolactam, and secondaryamines such as dibutyl amine.

Triazine compounds of the type mentioned are described in U.S. Pat. No.4,939,213.

Conventional aminoplast crosslinking agents are well known in the artand are described in U.S. Pat. No. 5,256,452 at column 9, lines 10-28.Useful aminoplast resins are based on the addition products offormaldehyde with an amino- or amido-group carrying substance.Condensation products obtained from the reaction of alcohols andformaldehyde with melamine, urea or benzoguanamine are most common andmost often used herein. While the aldehyde employed is most oftenformaldehyde, other similar condensation products can be made from otheraldehydes, such as acetaldehyde, crotonaldehyde, acrolein, benzaldehyde,furfural, glyoxal, and the like.

Condensation products of other amines and amides can also be used, forexample, aldehyde condensates of triazines, diazines, triazoles,guanadines, guanamines, and alkyl- and aryl-substituted derivatives ofsuch compounds, including alkyl- and aryl-substituted ureas and alkyl-and aryl-substituted melamines. Non-limiting examples of such compoundsinclude N,N′-dimethyl urea, benzourea, dicyandiamide, formaguanamine,acetoguanamine, glycoluril, ammeline, 3,5-diaminotriazole,triaminopyrimidine, and 2-mercapto-4,6-diaminopyrimidine. The aminoplastcrosslinking agent may be monomeric or polymeric and may be partially orfully alkylated.

Generally, the auxiliary crosslinking agent is present in an amountranging from about 0 to about 50 weight percent on a basis of totalresin solids of the curable composition, often about 5 to about 40weight percent.

In a separate, particular embodiment of the present invention, thereaction product or composition of matter described above may be used ina curable composition comprising:

a) the reaction product or composition of matter described above,present as a crosslinking agent in an amount of 1 to 30 percent byweight based on the total weight of resin solids in the curablecomposition;

b) an aminoplast crosslinking agent, present in an amount of 15 to 50percent by weight based on the total weight of resin solids in thecurable composition; and

c) an acrylic polymer having functional groups that are reactive withthe crosslinking agents of a) and b), present in an amount of 20 to 84percent by weight based on the total weight of resin solids in thecurable composition.

Generally, the crosslinking agent a) is present in an amount rangingfrom about 1 to about 30 weight percent on a basis of total resin solidsof the curable composition as noted above, often about 5 to about 15weight percent.

The curable composition further includes an aminoplast crosslinkingagent b). Useful aminoplast resins include any of those disclosed above.

Generally, the aminoplast crosslinking agent b) is present in an amountranging from about 15 to about 50 weight percent on a basis of totalresin solids of the curable composition as noted above, often about 20to about 35 weight percent.

The acrylic polymer c) is typically present in an amount ranging fromabout 20 to about 84 weight percent on a basis of total resin solids ofthe curable composition as noted above, often about 45 to about 70weight percent.

The acrylic polymer c) is typically a copolymer of one or more alkylesters of acrylic acid or methacrylic acid optionally together with oneor more other polymerizable ethylenically unsaturated monomers asdiscussed above.

The acrylic polymer often has beta-hydroxy ester functionality and, in aspecific embodiment, comprises a polymer of:

1) an ethylenically unsaturated, beta-hydroxy ester functional monomer;

2) about 5 to about 50, often 10 to 30, percent by weight, based ontotal solid weight of monomers used to prepare the polymer, of apolymerizable ethylenically unsaturated, hydroxyalkyl functional monomerdifferent from 1);

3) about 0 to about 40 percent by weight based on the total solid weightof monomers used to prepare the monomer of a vinyl aromatic monomer;

4) about 0 to about 60, often 0 to 30, percent by weight, based on thetotal solid weight of monomers used to prepare the polymer, of at leastone alkyl ester of acrylic acid or methacrylic acid; and

5) about 0 to about 20 percent by weight, based on the total solidweight of monomers used to prepare the polymer, of at least oneethylenically unsaturated monomer different from 1), 2), 3), and 4)above.

The beta-hydroxy ester functional monomer can be prepared fromethylenically unsaturated, epoxy functional monomers reacted withcarboxylic acids having from about 1 to about 20 carbon atoms, or fromethylenically unsaturated acid functional monomers reacted with epoxycompounds containing at least 4 carbon atoms that are not polymerizablewith the ethylenically unsaturated acid functional monomer. Suchmonomers are discussed above.

The beta-hydroxy ester functional monomer is typically present in thepolymer in an amount of 1 to about 70 percent, often about 10 to about70, more often about 20 to about 55 percent by weight, based on thetotal solid weight of monomers used to prepare the polymer.

Hydroxyethyl methacrylate is the most often used hydroxyalkyl monomer2), and is typically present in an amount of about 10 to about 30percent by weight, based on the total solid weight of monomers used toprepare the polymer. Suitable vinyl aromatic monomers and acrylic ormethacrylic acid esters include those disclosed above.

In addition to hydroxyl groups, the polymer may have carbamatefunctional groups. Such groups may be incorporated into the polymer asdiscussed above.

The acrylic polymer used in the curable composition typically has aweight average molecular weight of about 2,000 to about 25,000, often3,000 to 10,000 as determined by gel permeation chromatography using apolystyrene standard. The hydroxyl equivalent weight of the polymer isgenerally about 200 to about 800, often about 300 to about 500.

In each embodiment of the present invention, the curable compositionsmay optionally contain a mixture of other polymers separate from and inaddition to the functional group-containing polymer(s) that are reactivewith the crosslinking agent(s). The additional polymer(s) may or may notcontain functional groups and may be selected from acrylic polymers,polyester polymers, which are most often used, polyurethane polymers,polyether polymers, polysiloxane polymers, polyolefins, and mixturesthereof. These polymers are often hydroxyl or carbamate functional andmay be prepared as discussed above. Other functional groups includeepoxide, silane, carboxylic acid, anhydride, and the like.

When the curable compositions of the present invention containadditional functional group-containing polymers, the additional polymersare present in total amounts up to 50, often about 5 to 35, more often 5to 20 percent by weight based on the total weight of resin solids in thecurable composition.

In each embodiment of the present invention, the curable composition mayfurther include one or more auxiliary crosslinking agents as disclosedabove, such as free and/or capped polyisocyanates; triazine compounds ofthe formula: C₃N₃(NHCOXR)₃, wherein X is nitrogen, oxygen, sulfur,phosphorus, or carbon, and R is a lower alkyl group having one to twelvecarbon atoms, or mixtures of lower alkyl groups; and conventionalaminoplast crosslinking agents.

Other optional ingredients, such as catalysts, plasticizers,anti-oxidants, thixotropic agents, hindered amine light stabilizers, UVlight absorbers and stabilizers may be formulated into the curablecompositions of the present invention. These ingredients may be present(on an individual basis) in amounts up to 10 percent, often from about0.1 to 5 percent by weight based on total weight of resin solids of thecurable composition. Suitable catalysts include acid functionalcatalysts known to those skilled in the art as useful inaminoplast-cured compositions, such as phenyl acid phosphate,para-toluenesulfonic acid, dodecylbenzene sulfonic acid, and the like.

The curable compositions of the present invention may be used as curablefilm-forming compositions and may contain color pigments conventionallyused in surface coatings and may be used as high gloss monocoats; thatis, high gloss pigmented coatings. By “high gloss” it is meant that thecured coating has a 20° gloss and/or a DOI (“distinctness of image”)measurement of at least about 80 as measured by standard techniquesknown to those skilled in the art. Such standard techniques include ASTMD523 for gloss measurement and ASTM E430 for DOI measurement.

In specific embodiments of the present invention, suitable polymers oroligomers containing functional groups reactive with the crosslinkingagent(s) may be used (either by themselves, combined with one another,or in combination with other polymers or oligomers) to provide coatingswith flexibility acceptable for use over flexible plastic substrates.Nonlimiting examples of such polymers or oligomers are described in theexamples below. By flexible plastic substrates is meant any of thecommon thermoplastic or thermoset synthetic materials, which wouldinclude but not be limited to polyethylene, polypropylene, thermoplasticpolyolefin (TPO), reaction injected molded polyurethane (RIM), andthermoplastic polyurethane (TPU).

A specific application of the present invention is as a protective anddecorative coating for pigmented plastic substrates, or mold-in-color(MIC) plastic. The curable compositions of the present invention may beapplied as a high gloss clear monocoat directly to the pigmented plasticor applied over a clear adhesion promoter or clear primer which is onthe surface of the pigmented plastic. One example of a clear adhesionpromoter is MPP-4205 and is available from PPG Industries, Inc.

The curable compositions of the present invention are additionally oftenused as clear coats in multi-component composite coating compositionssuch as color-plus-clear composite coating compositions. Acolor-plus-clear composition typically comprises a base coat depositedfrom a pigmented or colored film-forming composition, and a transparenttopcoat (clear coat) applied over the base coat.

The multi-component composite coating compositions can be applied tovarious substrates to which they adhere, including wood, metals, glass,cloth, polymeric substrates, and the like. They are particularly usefulfor coating metals and elastomeric substrates that are found on motorvehicles. The compositions can be applied by conventional meansincluding brushing, dipping, flow coating, spraying, and the like, butthey are most often applied by spraying. The usual spray techniques andequipment for air spraying and electrostatic spraying and either manualor automatic methods can be used.

First, a base coat composition is applied to the surface of thesubstrate to be coated. The base coat composition can be waterborne,solventborne or powdered, and typically includes a film-forming resin,crosslinking material (such as are discussed above), and pigment.Non-limiting examples of suitable base coat compositions includewaterborne base coats for color-plus-clear composites such as aredisclosed in U.S. Pat. Nos. 4,403,003; 4,147,679; and 5,071,904, each ofwhich is incorporated by reference herein.

After application of the base coat to the substrate, there is typicallya drying or flash-off period allowed prior to the application of theclear coat. The purpose of this period is to evaporate at least aportion of the solvent or water from the base coat film. The flash-offconditions may vary by time, temperature, and/or humidity, depending onthe particular base coat composition, the desired appearance, andproperties of the final film. Typical times are from 1 to 15 minutes ata temperature between 70° F. and 250° F. (21.1° C. and 121.1° C.) Morethan one base coat layer and multiple topcoat layers may be applied tothe substrate to develop optimum appearance. Typically, the base coatthickness ranges from about 0.1 to about 5 mils (about 2.54 to about 127microns), and often about 0.4 to about 1.5 mils (about 10.16 to about38.1 microns) in thickness.

After application of the base coat, the topcoat described in detailabove is applied. The topcoat coating composition can be applied to thesurface of the base coat by any of the coating processes discussed abovefor applying the base coat coating composition to the substrate. Thecoated substrate is then heated to cure the coating layers. In thecuring operation, solvents are driven off and the film-forming materialsof the clear coat and the base coat are each crosslinked. The heating orcuring operation is usually carried out at a temperature in the range offrom 160° F.-350° F. (71° C.-177° C.) but, if needed, lower or highertemperatures may be used as necessary to activate crosslinkingmechanisms. The thickness of the clear coat usually ranges from about0.5 to about 5 mils (about 12.7 to about 127 microns), often about 1.0to about 3 mils (about 25.4 to about 76.2 microns).

As used herein, the term “cure” as used in connection with acomposition, e.g., “a curable composition,” shall mean that anycrosslinkable components of the composition are at least partiallycrosslinked. In certain embodiments of the present invention, thecrosslink density of the crosslinkable components, i.e., the degree ofcrosslinking, ranges from 5% to 100% of complete crosslinking. In otherembodiments, the crosslink density ranges from 35% to 85% of fullcrosslinking. In other embodiments, the crosslink density ranges from50% to 85% of full crosslinking. One skilled in the art will understandthat the presence and degree of crosslinking, i.e., the crosslinkdensity, can be determined by a variety of methods, such as dynamicmechanical thermal analysis (DMTA) using a Polymer Laboratories MK IIIDMTA analyzer conducted under nitrogen. This method determines the glasstransition temperature and crosslink density of free films of coatingsor polymers. These physical properties of a cured material are relatedto the structure of the crosslinked network.

According to this method, the length, width, and thickness of a sampleto be analyzed are first measured, the sample is tightly mounted to thePolymer Laboratories MK III apparatus, and the dimensional measurementsare entered into the apparatus. A thermal scan is run at a heating rateof 3° C./min, a frequency of 1 Hz, a strain of 120%, and a static forceof 0.01N, and sample measurements occur every two seconds. The mode ofdeformation, glass transition temperature, and crosslink density of thesample can be determined according to this method. Higher crosslinkdensity values indicate a higher degree of crosslinking in the coating.

The curable compositions of the present invention, when used asfilm-forming compositions, demonstrate improved acid resistance anddecreased photo-oxidation rates when compared to similar compositionsthat do not contain the reaction product or composition of matterdescribed above, but instead are formulated with conventional aminoplastcrosslinking agents. Not intending to be bound by any theory, it isbelieved that triazine rings present in conventional aminoplastcrosslinking agents in coating compositions undergo photo-oxidation whenexposed to ultraviolet radiation, leading to degradation of a curedfilm. Curable compositions of the present invention, containing thereaction product or composition of matter of the present invention, donot photo-oxidize as rapidly as conventional compositions.

The determination of acid resistance of a coating may be performed asfollows:

Coated test panels measuring at least 4″×8″ (10.16 cm×20.32 cm) areexposed in Jacksonville, Fla. from the last week of May through the lastweek of August of a calendar year. This is the standard location andexposure period (summer months) established by the North Americanautomobile manufacturers. Upon exposure completion, the panels are handwashed with soap and water, and then rinsed with water. The rinse wateris removed by squeegee, and then the panels are allowed to dry at roomtemperature. The panels are rated on a scale of 0 to 10 against a set ofreference standards comparable to those used by General Motors Company.A rating of ‘0’ is outstanding, with no visible etching orwaterspotting. The severity of etch steadily increases up through therating of ‘10’, which is severe etching and waterspotting. Thedetermination of the photo-oxidation rate of a coating may be performedaccording to Ford Motor Company's Exterior Paint Weathering Test MethodPA-0148, DVM-5867.

The present invention will further be described by reference to thefollowing examples. The following examples are merely illustrative ofthe invention and are not intended to be limiting. Unless otherwiseindicated, all parts are by weight.

EXAMPLE A

A butylated, etherified carbamate crosslinking agent was prepared fromthe following ingredients:

Ingredients Wt. in grams Charge 1 DESMODUR N 3300¹ 873.0 Dibutyltindilaurate 0.21 Methyl isobutyl ketone 675.0 Charge 2 Hydroxypropylcarbamate 535.50 Charge 3 Butanol 1665.0 FORMCEL 53% n-butanol/40%formaldehyde solution² 675.0 Phosphoric acid (85% solution) 9.00 ¹Trimerof 1,6-hexamethylene diisocyanate available from Bayer Corp. ²Availablefrom Chemicals Division, Celanese Ltd.

The ingredients of Charge 1 were added to a flask equipped with anoverhead stirrer, reflux condenser, thermocouple, and N₂ inlet andheated to 60° C. Charge 2 was then added over a period of 2 hours,maintaining the temperature between 60° C. and 65° C. and then held for2 hours. After the hold, a small amount of isocyanate was detected by IRspectroscopy; hydroxypropyl carbamate (5 g) was added to react off theresidual isocyanate groups. After IR spectroscopy determined that theisocyanate was completely consumed, the flask was equipped for simplevacuum distillation and methyl isobutyl ketone was stripped from thereaction mixture under reduced pressure at s temperature between 67° C.and 107° C. Charge 3 was then added to the reaction mixture in the ordergiven and the flask was equipped with a reflux condenser and a DeanStark trap filled with butanol. The reaction was reheated to reflux andH₂O was removed by azeotropic distillation. Reflux conditions weremaintained until 182 g of H₂O was collected. The resulting resin had ameasured solids content (110° C., 1 hour) of 52.5%, a Gardner-Holtviscosity of F, a number average molecular weight of 4772, and a weightaverage molecular weight of 6867 as determined by gel permeationchromatography using a polystyrene standard.

EXAMPLE B

A carbamate functional urethane resin was prepared from the followingingredients:

Ingredients Wt. in grams Charge 1 DESMODUR N 3300¹ 1164.0 Dibutyltindilaurate 0.30 DOWANOL PM acetate³ 480.0 Charge 2 Hydroxypropylcarbamate 749.7 Charge 3 Isobutanol 1332.0 ³1-methoxy-2-propanolacetate, available from Dow Chemical Company.

The ingredients of Charge 1 were added to a flask equipped with anoverhead stirrer, reflux condenser, thermocouple, and N₂ inlet andheated to 60° C. Charge 2 was then added over a period of 3.5 hours,maintaining the temperature between 60° C. and 65° C. and then held for1.75 hours. IR spectroscopy determined that the isocyanate wascompletely consumed. The reaction mixture was then thinned with Charge3. The resulting resin had a measured solids content (110° C., 1 hour)of 54.1%, a Gardner-Holt viscosity of O—, a number average molecularweight of 1782, and a weight average molecular weight of 2442 asdetermined by gel permeation chromatography using a polystyrenestandard.

EXAMPLE C

An isobutylated/butylated etherified carbamate crosslinking agent wasprepared from the following ingredients:

Ingredients Wt. in grams DESMODUR N 3300/hydroxypropyl carbamate 372.0adduct solution in DOWANOL PM acetate and isobutanol of Example BIsobutanol 177.6 FORMCEL 53% n-butanol/40% formaldehyde solution² 90.0Phosphorous acid 3.06

The ingredients were added to a flask equipped with an overhead stirrer,reflux condenser, Dean Stark trap filled with isobutanol, thermocouple,and N₂ inlet. The reaction mixture was heated to reflux (101° C.), atwhich time H₂O began to be collected in the Dean Stark trap. As H₂Oevolution progressed the temperature of the reaction mixture wasincreased in stages in order to maintain reflux. The reaction mixturewas thus held for 3 hours from the time of initial reflux onset, atwhich time 22 g of H₂O had been collected and a temperature of 111° C.had been attained. The resulting resin had a measured solids content(110° C., 1 hour) of 41.1%, a Gardner-Holt viscosity of A-B, a numberaverage molecular weight of 3070, and a weight average molecular weightof 6192 as determined by gel permeation chromatography using apolystyrene standard.

EXAMPLE D

A carbamate functional urethane resin was prepared from the followingingredients:

Ingredients Wt. in grams Charge 1 DESMODUR N 3300¹ 1164.0 Dibutyltindilaurate 0.30 DOWANOL PM acetate³ 480.0 Charge 2 Hydroxypropylcarbamate 749.7 Charge3 Methanol 888.0 ³1-methoxy-2-propanol acetate,available from Dow Chemical Company.

The ingredients of Charge 1 were added to a flask equipped with anoverhead stirrer, reflux condenser, thermocouple, and N₂ inlet andheated to 60° C. Charge 2 was then added over a period of 2.8 hours,maintaining the temperature between 60° C. and 65° C. and then held for3 hours. IR spectroscopy determined that the isocyanate was completelyconsumed. The reaction mixture was then thinned with Charge 3. Theresulting resin had a measured solids content (110° C., 1 hour) of59.4%, a Gardner-Holt viscosity of C-D, a number average molecularweight of 1753, and a weight average molecular weight of 2350 asdetermined by gel permeation chromatography using a polystyrenestandard.

EXAMPLE E

A methylated, etherified carbamate crosslinking agent was prepared fromthe following ingredients:

Ingredients Wt. in grams DESMODUR N 3300/hydroxypropyl carbamate 820.0adduct solution in DOWANOL PM acetate and methanol of Example D Methanol37.4 FORMCEL 55% formaldehyde/35% methanol solution² 163.7 Phosphoricacid (85% in H₂0) 9.0

The ingredients were added to a flask equipped with an overhead stirrer,reflux condenser, thermocouple, and N₂ inlet. The reaction mixture washeated to reflux (76° C.-77° C.). This temperature was maintained andthe progress of the reaction was periodically monitored by infraredspectroscopy. The reaction mixture was held at reflux for 5 hours, atwhich time no further changes in the infrared spectrum were evident. Theresulting resin had a measured solids content (110° C., 1 hour) of58.9%, a Gardner-Holt viscosity of B-C, a number average molecularweight of 1812, and a weight average molecular weight of 2796 asdetermined by gel permeation chromatography using a polystyrenestandard.

EXAMPLE F

A carbamate functional polyester was prepared from the followingingredients:

Ingredients Wt. in grams Charge 1 Polyester⁴ 6916.4 Methyl carbamate1081.4 Butyl stannoic acid 14.4 Triphenyl phosphite 14.4 DOWANOL PM⁵1297.7 Charge 2 DOWANOL PM acetate 1647.6 Charge 3 DOWANOL PM 1294.5⁴Made from hexahydrophthalic anhydride/neopentylglycol/2,2,4-trimethyl-1,3-pentanediol/trimethylolpropane in a49.2:17.5:22.7:10.6 weight ratio, 100% solids. ⁵1-methoxy-2-propanol,available from Dow Chemical Company.

Charge 1 was added to a reactor equipped with an overhead stirrer,thermocouple, N₂ inlet, and reflux condenser, heated to reflux (141°C.), and held 1 hour. The reflux condenser was then removed and theflask was equipped for atmospheric distillation with a short packedcolumn and thermocouple head temperature probe. Over a period of 3.8hours the temperature was raised to 151° C. to maintain distillation ata head temperature <81° C. At this point, 422 g of distillate had beencollected. Vacuum was then applied to the system to continue thedistillation process. The temperature of the system was allowed to dropto 140° C.-141° C. while the pressure was reduced to maintaindistillation. When a pressure of 60 mm Hg was obtained the reactionmixture was held at this pressure for 1 hour. The amount of distillatecollected under vacuum was 1007 g. The reaction mixture was then sampledand the OH value of the resin was found to be 32.6. The reaction mixturewas then thinned with Charge 2, followed by Charge 3. The resultingresin solution had a measured solids content (110° C., 1 hour) of 70.2%,a Gardner-Holt viscosity of Z1+, a final OH value (at 100% solids) of37.4, a number average molecular weight of 1160, and a weight averagemolecular weight 2539 as determined by gel permeation chromatographyusing a polystyrene standard.

EXAMPLE G

A carbamate functional acrylic polymer was prepared from the followingingredients:

Ingredient Wt. in parts Charge 1 Acrylic polyol⁶ 2910.0 Charge 2 Methylcarbamate 408.0 DOWANOL PM⁵ 20.0 Charge 3 Triphenylphosphite 6.7 Butylstannoic acid 5.6 DOWANOL PM 7.0 Charge 4 Ethyl-3-ethoxyproprionate620.0 Charge 5 DOWANOL PM 620.0 ⁶Made from butyl methacrylate,hydroxypropyl acrylate, and methyl styrene dimer in a 58:40:2 weightratio, approximately 6500 M_(w), 78.1% solids in DOWANOL PM.

Charges 1, 2 and 3 were added in order to a reactor equipped with anoverhead stirrer, thermocouple, N₂ inlet, and reflux condenser, heatedto reflux (135° C.), and held 1 hour. The reactor was then convertedover to atmospheric distillation with a packed column. Over a period of3 hours the temperature was raised to 140° C. to maintain distillation.At this point, 67 parts of distillate had been collected. Vacuum wasthen applied to the system to continue the distillation process. Thetemperature of the system was held between 132° C. and 143° C. while thepressure was gradually reduced to maintain distillation until a reactorpressure of 36 mm Hg was obtained. The amount of distillate collectedunder vacuum was 769 parts. The reaction mixture was sampled and foundto have an OH value of 42.5. Vacuum was broken and Charge 4 was added tothe reaction mixture, followed by Charge 5. The resulting resin solutionhad a measured solids content (110° C., 1 hour) of 64.3%, a Gardner-Holtviscosity of Z-, a number average molecular weight of 2999, and a weightaverage molecular weight 8434 as determined by gel permeationchromatography using a polystyrene standard.

EXAMPLE H

A carbamate functional polyether was prepared from the followingingredients:

Ingredient Weight in grams TERATHANE 1000⁷ 1400.2 Methyl carbamate 210.3Butyl stannoic acid 4.9 Triphenylphosphite 3.2 DOWANOL PM 269.7⁷Polytetramethylene glycol having an M_(n)of 950 to 1050 and an OH valueof 7 to 118, available from E.I. du Pont de Nemours and Co., Inc.

A suitable reactor was charged with the above ingredients and equippedwith a thermocouple, overhead stirrer, nitrogen inlet and a refluxcondenser. The material was heated to 143° C. under a nitrogen blanket.At this temperature reflux was observed; the reaction mixture was heldat this temperature for one hour. After the hold period was complete,the reaction mixture was cooled to 135° C., the reflux condenser wasremoved, and the reactor equipped for distillation (short packed column,still head, thermocouple, condenser, and receiver flask) at atmosphericpressure. Distillate began to come over at 141° C., the temperature wasgradually raised to 155° C. to maintain distillation. At this point 79.3g of distillate had been collected. The reaction mixture was then cooledto 140° C. and equipped for simple vacuum distillation (still head,thermocouple, condenser, vacuum adapter, receiver flask). Distillationwas resumed under reduced pressure; the pressure inside the reactor wasgradually reduced to maintain distillation until a reactor pressure of60 mm Hg was attained. When the distillation was essentially stopped,the reaction mixture was sampled and the hydroxyl value found to beacceptable. The additional distillate collected totaled 258.3 g. Thecontents of the reactor were then poured out. The resulting material wasa slightly hazy liquid when warm with a color of 40 as measured on theAPHA scale; it solidified to a soft, white, waxy opaque material uponstanding at ambient temperature. The final material was found to have ahydroxyl value of 15.8, a measured solids of 98.4%, a weight averagemolecular weight of 3384, and a number average molecular weight of 1515as determined by gel permeation chromatography using a polystyrenestandard.

EXAMPLE I

A siloxane polyol was prepared from the following ingredients:

Ingredient Wt. in parts Charge 1 Trimethylolpropane monoallyl ether131.5 Charge 2 MASILWAX BASE⁸ 93.2 Charge 3 Chloroplatinic acid 0.0047Toluene 0.23 Isopropanol 0.07 ⁸Reactive silicone prepolymer availablefrom BASF Surfactants.

To a suitable reaction vessel equipped with an overhead stirrer,thermocouple, reflux condenser, and N₂ inlet, Charge 1 and an amount ofsodium bicarbonate equivalent to 20 to 25 ppm of total Charge 1 andCharge 2 solids were added at ambient temperature. The temperature ofthe reaction mixture was gradually increased to 75° C. under a nitrogenblanket. At that temperature, about 5 percent of Charge 2 was addedunder agitation, followed by the addition of Charge 3. The reaction wasthen allowed to exotherm to 95° C. at which time the remainder of Charge2 was added at a rate such that the temperature did not exceed 95° C.After completion of this addition, the reaction mixture was maintainedat a temperature of 95° C. and held until the silicon hydride absorptionband (Si—H, 2150 cm⁻¹) was no longer present in the infrared spectrum ofthe material.

EXAMPLE J

A colloidal silica dispersion was prepared from the followingingredients:

Ingredients Wt. in grams Siloxane polyol of Example I 701.1 Colloidalsilica⁹ 1001.7 Methyl amyl ketone 320.0 ⁹MT-ST colloidal silicadispersion in methanol available from Nissan Chemical.

A suitable reactor equipped with an overhead stirrer, thermocouple, andN₂ inlet was set up for vacuum distillation and flushed with N₂. Theabove ingredients were then added to the flask and methanol distilledfrom the resulting mixture under reduced pressure at a temperature below35° C. The distillation was continued until no addition distillate isobtained at a pressure of 70 mm Hg at 35° C.

EXAMPLE K

An acrylic polyol was prepared from the following ingredients:

Ingredients Wt. in grams Charge 1 SOLVESSO 100¹⁰ 647.7 CARDURA E¹¹ 659.0Zinc octoate 2.8 Xylene 431.8 Charge 2 di-t-amyl peroxide 45.9 SOLVESSO100 109.2 Charge 3 Styrene 690.0 Hydroxyethyl methacrylate 457.72-ethylhexyl acrylate 276.0 Acrylic acid 217.4 Charge 4 SOLVESSO 10083.1 ¹⁰Blend of aromatic solvents available from Exxon ChemicalsAmerica. ¹¹Glycidyl ester of branched Cl0 saturated carboxylic acidavailable from Shell Chemical Co.

The ingredients of Charge 1 were added to a flask equipped with a refluxcondenser, stirrer, thermocouple, and N₂ inlet and heated to reflux(164° C.). Charges 2 and 3 were started simultaneously; Charge 2 wasadded over 4.25 hours, and Charge 3 was added over 4 hours. The reactionwas maintained at reflux throughout the addition of Charges 2 and 3. Thereaction mixture was held at reflux temperature for 1 hour after thecompletion of Charge 3 and thinned with Charge 4. The resulting resinsolution had a measured solids content (110° C., 1 hour) of 64.6%, aGardner-Holt viscosity of Z3-, an acid value of 11.8, a number averagemolecular weight of 2852, and a weight average molecular weight 8589 asdetermined by gel permeation chromatography using a polystyrenestandard.

FLEXIBLE COATING EXAMPLES

The following examples describe the preparation of a film-formingcomposition used as the transparent topcoat in a multi-componentcomposite coating composition of the present invention. Coating examples2, 3, and 5 contain the reaction product of Example A. Comparativeexamples 1 and 4 do not, but rather contain conventional aminoplast(melamine) crosslinking agents. The film-forming compositions wereprepared from a mixture of the following ingredients under agitation inthe order in which they appear:

Comparative Example Example 2 Example 3 Solid Total Solid Total SolidTotal Weight Weight Weight Weight Weight Weight in in in in in inIngredients Grams Grams Grams Grams Grams Grams Methyl acetate — 13.4 —13.4 — 13.4 n-butyl alcohol — 8.6 — 8.6 — 8.6 Xylene — 1.3 — 1.3 — 1.3Butyl acetate — 6.0 — 6.0 — 6.0 DMPA glycol — 5.3 — 5.3 — 5.3 etheracetate¹ Chisorb 328² 3.2 3.2 3.2 3.2 3.2 3.2 Flow control 2.1 4.7 2.14.7 2.1 4.7 agent³ CYMEL 1130⁴ 20.3 20.3 — — — — MR-225⁵ 5.4 8.3 — — — —Flow control 8.2 20.0 8.2 20.0 8.2 20.0 agent⁶ Polybutyl 0.25 0.4 0.250.4 0.25 0.4 acrylate solution⁷ Surface tension 0.015 0.15 0.015 0.150.015 0.15 modifier⁸ Anti silk 0.003 0.5 0.003 0.5 0.003 0.5 agents⁹Neutralized 0.8 1.7 0.8 1.7 0.8 1.7 HALS solution¹⁰ Catalyst 1.5 2.1 1.52.1 1.5 2.1 solution¹¹ Diisopropanol — 1.0 — 1.0 — 1.0 amine (50% inethanol) Carbamate 13.5 21.4 13.5 21.4 13.5 21.4 functional acrylicpolymer of Example G Carbamate 31.1 43.2 31.1 43.2 39.8 55.3 functionalpolyester polymer of Example F Carbamate 20 20.0 20 20.0 — — functionalpolyether polymer of Example H Acrylic 3.0 4.5 3.0 4.5 — — polyol¹²Reaction — — 25.7 49.0 40.0 68.1 product of Example A ¹DMPA glycol etheracetate solvent available from DOW Chemical ²Substituted benzotriazoleUV light stabilizer available from Chitec Chemical Co. ³Polymericmicroparticle prepared in accordance with example 11 of U.S. Pat. No.4,147,688 ⁴Fully alkylated melamine-formaldehyde aminoplast resinavailable from Cytec Industries, Inc. ⁵Polymeric alkylatedmelamine-formaldehyde aminoplast resin available from Solutia⁶Dispersion of 7.7% Aerosil R812 silica (available from Degussa) inacrylic polyol ‘d’ ⁷A flow modifier having a Mw of about 6700 and Mn ofabout 2600 made in xylene at 62.5% solids ⁸10% Baysilone OL 17,available from Bayer Corporation, in 2-methoxy propyl acetate ⁹0.5%DC200 100CS silicone, available from Dow Corning, in xylene ¹⁰Solutionof 25% Tinuvin 292, available from Ciba-Geigy Corporation, 24.5% dodecylbenzene sulfonic acid, 40% isobutyl alcohol, and 10.5% isopropyl alcohol¹¹Dodecyl benzene sulfonic acid solution ¹²Acrylic polyol of composition(40 Hydroxypropyl acrylate/20 styrene/19 butyl acrylate/18.5 butylmethacrylate/2 acrylic acid/0.5 methyl methacrylate); 67% solids; Mw =7,000 Comparative Example 4 Example 5 Solid Total Solid Total WeightWeight Weight Weight in in in in Ingredients Grams Grams Grams GramsAcetone — 20.0 — 20.0 Ethyl-3-ethoxy propionate — 30.0 — 30.0 2-methoxypropyl acetate — 15.0 — 15.0 Tinuvin 328¹ 3.0 3.0 3.0 3.0 Tinuvin 292²0.5 0.5 — — Tinuvin 123³ 0.6 0.6 1.1 1.1 Surface tension modifier⁴ 0.040.24 0.04 0.24 Surface tension modifier⁵ 0.03 0.13 0.03 0.13 Acrylicpolyol⁶ 53.7 89.5 53.7 89.5 Polyester polyol⁷ 5.0 6.3 5.0 6.3 Silicadispersion of 7.1 9.4 7.1 9.4 Example J Cymel 202⁸ 15.0 18.8 — —Reaction product of — — 15.0 25.6 Example A The following were added andmixed within 5 minutes prior to application: DesmodurN-3300⁹ 21.3 21.321.3 21.3 Phenyl acid phosphate¹⁰ 1.0 1.3 1.0 1.3 ¹Substitutedbenzotriazole UV light stabilizer available from Ciba Geigy Corporation²Sterically hindered amine light stabilizer available from Ciba GeigyCorporation ³Sterically hindered amine light stabilizer available fromCiba Geigy Corporation ⁴Solution of BYK 310 (available from BYK Chemie),15% in 2-methoxy propyl acetate ⁵Solution of BYK 307 (available from BYKChemie), 25% in 2-methoxy propyl acetate ⁶Acrylic polyol: (1.0%methacrylic acid/23.4% 2-ethylhexyl methacrylate/20.8% 2-ethylhexylacrylate/20% styrene/34.8% hydroxyethylmethacrylate) 60% in46.4:46.0:7.6 DOWANOL PM acetate/butyl acetate/odorless mineral spirits,hydroxyl value = 90 on solution, Gardner- Holt = T ⁷Polyester polyol:(32% 4-methyl hexahydrophthalic anhydride/22.9% 1,6 hexane diol/ 18.6%trimethylol propane/18.4% adipic acid/8.1% trimethyl pentane diol), 80%in 60:40 butyl acetate/Solvesso 100, hydroxyl value = 145, Gardner-Holtviscosity = X − Z ⁸Partially alkylated melamine-formaldehyde aminoplastresin available from Cytec Industries ⁹Polyisocyanate resin availablefrom Bayer Corporation ¹⁰Phenyl acid phosphate solution available fromRhodia

Test Panel Preparation:

MPP4100D, high solids adhesion promoter commercially available from PPGIndustries, Inc., was applied to Sequel 1440 TPO plaques, commerciallyavailable from Standard Plaque (4 inches×12 inches; 10.16 cm×30.48 cm),by hand spraying at a dry film thickness of 0.15 mils to 0.25 mils (3.8microns to 6.4 microns). Each Sequel 1440 plaque was cleaned withisopropyl alcohol prior to being promoted. The promoted Sequel 1440plaques sat for up to one day before a solventborne black base coatcommercially available from PPG Industries, Inc., CBCK8555A, was appliedat a dry film thickness of 0.8 mils to 1.2 mils (20.3 microns to 30.5microns). The base coat was applied by Spraymation® in two coats with a90 second “flash” at ambient temperatures between each coat. ForExamples 1, 2, and 3, the base coated panels were baked for 10 minutesat 254° F. (123.3° C.) prior to application of the transparent topcoatsdescribed in the above examples. For examples 4 and 5, the base coatedpanels sat at ambient temperature for 90 seconds before the transparenttopcoats described in the above flexible examples were applied.Application of the transparent topcoats was by Spraymation® in two coatswith a 90-second ambient flash between each coat. The transparenttopcoats had a dry film thickness between 1.5 mils and 2.0 mils (40.6microns to 45,7 microns). The top coated panels were allowed to sit atambient temperature for 10 minutes and then were thermally cured at 254°F. (123.3° C.) for 40 minutes. The coated test panels sat at ambienttemperature for a minimum of four days prior to testing.

The test panels coated with flexible examples 1 through 5 were evaluatedfor flexibility, acid etch resistance, and photo-oxidative degradationrate. Flexibility was evaluated at 70° F. (21.1° C.). For flex testing,a 1-inch by 4-inch (2.54 cm×10.16 cm) piece was cut from the coated testpanel. The piece was subjected to a bend around a ½ inch (1.27 cm)diameter steel mandrel, such that the two ends of the 4-inch long (10.16cm) test piece contacted one another. The rating scale is from 0 to 10.A ‘10’ consists of no paint cracking. A ‘9’ has less than fiveinterrupted short line cracks. An ‘8’ has interrupted line cracks with amaximum of four uninterrupted line cracks. A ‘6’ has five to tenuninterrupted line cracks. A ‘4’ has more than 15 uninterrupted linecracks. A ‘0’ is fracture of the substrate.

Acid etch resistance was measured by exposing a 4″×8″ (10.16 cm×20.32cm) coated test panel in Jacksonville, Fla. from the last week of Maythrough the last week of August 2001. Upon exposure completion, thepanels were hand washed with soap and water, and then rinsed with water.The rinse water was removed by squeegee, and then the panels wereallowed to dry at room temperature. The panels were rated on a scale of0 (outstanding) to 10 (severe etching) against a set of referencestandards comparable to those used by General Motors.

Photo-oxidation rate is a measure of how rapidly an organic coatingphoto-oxidatively degrades. The higher the numerical rating, the morerapidly the coating photo-oxidatively degrades. The panels were testedaccording to Ford Motor Company's Exterior Paint Weathering Test MethodPA-0148, DVM-5867. Results are shown on the following table.

Photo-oxidation Rate Etch 1000 hrs EXAMPLE Flexibility AcidWeatherometer Comparative 10 10 0.648 Example 1 Example 2 10 10 0.369Example 3 10 5 0.250 Comparative 8 7 0.467 Example 4 Example 5 8 6 0.286

The data in the table illustrate that compositions prepared inaccordance with the present invention demonstrate acid etch andflexibility properties comparable or superior to analogous conventionalcompositions containing aminoplast resins as the crosslinking agent.Particularly notable is the improved photo-oxidation rate of thecompositions of the present invention, as well as the flexibility of thecomposition of example 3, despite the lack of polyether resin therein.

The following examples describe the preparation of a film-formingcomposition used as the transparent topcoat in a multi-componentcomposite coating composition of the present invention. Comparativeexample 6 contains a commercially available aminoplast crosslinkingagent. Comparative example 7 contains a commercially availableaminoplast and a commercially available triazine compound. Thecompositions of examples 8 and 9 were prepared in accordance with thepresent invention. Coating example 8 contains a commercially availableaminoplast and the reaction product of Example C. Coating example 9contains a commercially available aminoplast, a commercially availabletriazine compound, and the reaction product of Example C. Clearfilm-forming compositions were prepared by mixing together the followingingredients:

Comparative Comparative Example 6 Example 7 Example 8 Example 9 SolidWeight Total Weight Solid Weight Total Weight Solid Weight Total WeightSolid Weight Total Weight in Ingredients in Grams in Grams in Grams inGrams in Grams in Grams in Grams Grams Xylene — 10 — 10 — 10 — 10 Ethyl3-Ethoxy — 3.5 — 3.5 — 3.5 — 3.5 propionate Aromatic 150¹ — 5.6 — 5.6 —5.6 — 5.6 2-Butoxy ethanol acetate — 1.8 — 1.8 — 1.8 — 1.8 Butylcarbitol² — 2.9 — 2.9 — 2.9 — 2.9 Butyl ether diethylene glycol — 3.5 —3.5 — 3.5 — 3.5 acetate Aromatic 100³ — 4 — 4 — 4 — 4 Tinuvin 928⁴ 1 1 11 1 1 1 1 Irganox 1010⁵ 0.23 0.23 0.23 0.23 0.23 0.23 0.23 0.23 Tinuvin400⁶ 0.83 0.98 0.83 0.98 0.83 0.98 0.83 0.98 Tinuvin 292⁷ 0.80 0.80 0.800.80 0.80 0.80 0.80 0.80 Worlee Additive 315⁸ 0.06 0.60 0.06 0.60 0.060.60 0.06 0.60 Rheology Control Agent⁹ 25 41.6 25 41.6 23 38.3 25 41.6Catalyst Solution¹⁰ 0.50 0.70 0.50 0.70 1.0 1.4 0.50 0.70 Setamine US138¹¹ 34 48.6 29 42.9 27 38.6 29 41.4 Acrylic Polyol of Example K 4164.1 41 64.1 36 56.3 41 64.1 TACT¹² — — 5 9.7 — — 2.5 4.9 Reactionproduct of Example C — — — — 14 34.1 2.5 6.1 ¹Blend of aromatic solventsavailable from Exxon Chemicals America. ²Diethylene glycol monobutylether available from Union Carbide Chemicals and Plastics Co., Inc.³Blend of aromatic solvents available from Exxon Chemicals America⁴Substituted benzotriazole UV Light stabilizer available from Ciba GeigyCorporation. ⁵Anti-oxidant available from Ciba Specialty ChemicalsCorporation. ⁶Substituted triazine UV Light stabilizer available fromCiba Geigy Corporation. ⁷Sterically hindered amine light stabilizeravailable from Ciba Geigy Corporation. ⁸Flow additive available fromWorlee Chemie. ⁹Sag control agent available from Akzo Nobel. ¹⁰Dodecylbenzene sulfonic acid solution ¹¹A partially alkylated butoxy functionalaminoplast available from Akzo Nobel. ¹²Tris (alkyl carbamoyl) triazineavailable from Cytec Industries, Inc.

Clearcoat formulations examples 6-9 were reduced with Aromatic 100 byweight to 28″ #4 Ford at room temperature (71° F.-75° F., 21.7° C.-23.9°C). The film-forming compositions of examples 6-9 were applied topigmented base coats to form color-plus-clear composite coatings over asteel substrate with electrocoat primer and primer surfacer. The basecoat used for the examples is commercially available from PPGIndustries, Inc. and is identified as 259502 (black). The primer used iscommercially available from PPG Industries, Inc. and is identified as1177-422AR. The electrocoat used on the steel is commercially availablefrom PPG Industries, Inc. and is identified as ED5000.

The base coat was applied in two coats to the primed electrocoated steelpanels at a temperature of about 75° F. (23.9° C.). Approximately a 90seconds flash time was allowed between the two base coat applications.After the second base coat application, a 3 minutes flash time wasallowed at about 75° F. (23.9° C.) before the application of the clearcoating composition. The clear coating compositions of examples 6-9 wereeach applied to a base coated panel in two coats with a 60 seconds flashtime at 75° F. (23.9° C.) allowed between coats. The composite coatingwas allowed to air flash at 75° F. (23.9° C.) for 10 minutes beforebaking at 285° F. (140.6° C.) to cure both the base coat and clearcoat.The panels were baked in a horizontal position. The colored panel foreach clearcoat example was baked for 30 minutes and used to test forproperties. The dry film thickness ranges for the base coat andclearcoat were 0.5-0.6 mils (12.7-15.24 microns) and 1.5-1.6 mils(38.1-40.6 microns), respectively. The test panels coated with examples6 through 9 were evaluated for appearance, Crockmeter mar resistance,acid etch resistance, and humidity resistance. The property data hasbeen summarized in the following table.

Summary of Clearcoat Property Data Comparative Comparative ExampleExample #6 Example #7 #8 Example #9 20° Gloss 94 94 92 98 DOI 94 95 9396 % Mar Retention¹ 89 91 90 89 Acid Resistance² 74 86 84 73 Humidity³ 22 3 3 ¹Mar resistance of coated panels was measured using the followingmethod: Gloss of coated panels is measured with a MacBeth NOVOGLOSSStatistical 20 degree glossmeter. Coated panels are marred by applyingten double rubs to the surface using two-micron paper on a wool feltcloth using a Crockmeter ® mar tester (available from Atlas ElectricDevices Company). The 20 degree gloss is read on the marred area of thepanel after being # washed with water and patted dry. The numberreported is # the percent gloss retention after marring; i.e., 100% ×marred gloss/original gloss. ²Acid resistance was measured in terms of %20 degree gloss retention. Prior to testing, 20 degree glossmeasurements are recorded. A 5 centimeter PVC ring with a seal is placedon a clean panel surface. A solution containing sulfuric acid and ironsulfate (10 mL) is placed inside the PVC ring. A watch glass is placedover the PVC ring. The panel is placed on a 70° C. hot plate for 1 hour.After 1 # hour the watch glass and PVC ring are removed, the panel isrinsed with water, and the surface is wiped with mineral spirits. 20degree gloss measurements are taken of the tested area. The % 20 degreegloss retention is recorded. ³Four days exposure at 140° F. on a QCTcondensation tester (Q-Panel Company, Cleveland, OH). Panels were ratedfor blushing and blistering. Blush was rated on a scale of 0 to 5 (0 =no blush or color change, 5 = severe blush or color change.

The data in the table demonstrate that compositions prepared inaccordance with the present invention exhibit outstanding gloss, DOI,and mar resistance. Other properties are at least comparable to coatingcompositions prepared with conventional aminoplast crosslinking agents.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications that are within the spirit and scopeof the invention, as defined by the appended claims.

What is claimed is:
 1. A reaction product of reactants, wherein thereactants comprise: a) an isocyanurate; b) a hydroxyalkyl carbamate; c)an aldehyde; and d) at least one monohydric alcohol.
 2. The reactionproduct of claim 1 wherein the isocyanurate a) is derived fromhexamethylene diisocyanate or from isophorone diisocyanate.
 3. Thereaction product of claim 1, wherein the hydroxyalkyl carbamate isselected from at least one of hydroxypropyl carbamate and hydroxyethylcarbamate.
 4. The reaction product of claim 1 wherein the aldehyde isformaldehyde.
 5. The reaction product of claim 1 wherein the monohydricalcohol is selected from at least one of methanol, ethanol, n-propanol,isopropanol, n-butanol, isobutanol, and cyclohexanol.